This invention relates to a hand-holdable apparatus useful for abrading a surface, particularly the surface of a tooth using a stream of abrasive particles suspended in a gas stream. The invention is particularly useful for dental applications. The apparatus of the invention may be modified to easily minimize xe2x80x9cbleed downxe2x80x9d of the gas/abrasive stream using a pinch valve and to remove worn flexible conduits for routine maintenance of the apparatus. The apparatus of the invention also provides a novel pick-up assembly for delivery of abrasive particles.
A significant technology has developed relating to the use of small abrasive particles propelled by a compressed gas and directed against a surface to clean or abrade the surface. This gas/abrasion technique has developed to a significant degree for dental uses for doing pit and fissure work as well as for cutting enamel and dentin of teeth to repair cavities. In the dental field, the gas/abrasion technique has certain advantages over drilling with a high speed drill, e.g., less heat and pressure are generated. The early gas abrasive devices were cumbersome in that they required an abrasive particle container that was maintained separately from the nozzle means used to direct the stream of gas/abrasive particles against the surface of a tooth. See e.g., U.S. Pat. No. 2,696,049. Over the years devices were developed wherein the abrasive particles were contained in a holder that was associated with a nozzle as a hand-held unit. See for example U.S. Pat. No. 4,648,840. One of the problems with previous devices is that the control of the flow was done using a foot peddle, which did not give the user detailed control of the flow of the gas abrasive stream and often resulted in long bleed down times. We have now invented a hand holdable device having a flexible design allowing the user to regulate flow using a finger control and to minimize the bleed-down time when shutting off the gas/abrasive stream. The design also provides for the use of a pinch valve mechanism on a flexible line to regulate the flow of material. Preferably the flexible line is removable and thus making the hand holdable device autoclavable.
One aspect of this invention is an apparatus for delivering a stream of a mixture of a gas and a powdered abrasive material to a surface. The apparatus comprises:
(a) a container-receiving member for detachably receiving a container for the powdered abrasive material;
(b) a discharge nozzle for directing the stream of the mixture of the gas/abrasive material against a surface;
(c) a first optionally flexible conduit having one end in fluid communication with the discharge nozzle and the other end in fluid communication with the container, when attached, through the container-receiving member;
(d) a second optionally flexible conduit for connecting one end to an external gas source and the other end to the attachment portion for the abrasive material container;
(e) a pinch valve for pinching either the first or second flexible conduit to regulate the flow of the mixture of the gas/abrasive material to the discharge nozzle; and
(f) a housing for parts (a)-(e).
Another aspect of this invention is a hand-holdable apparatus for delivering a stream of a gas and a powdered abrasive material to a surface. The apparatus comprises:
(a) an abrasive material pick-up assembly comprising (i) a container-receiving member for detachably receiving a container for the powdered abrasive material, (ii) two conduits, an inner conduit defined by a surrounding wall having a distal end away from the container-receiving member and proximal end connected to the container-receiving member and an outer conduit defined by an outer wall, having analogous distal and proximal ends, wherein an intermediate passage is defined by the inner conduit wall and the outer-conduit wall, (iii) a container for holding the powdered abrasive material, the container having an open end and a closed end, which container is detachably connected to the container-receiving member through its open end and encloses the two conduits such that distal ends of the conduits are near the closed end of the container, (iv) a passageway through the wall of the inner conduit near its distal end, and (v) an optional passageway through the wall of the outer conduit near its distal end;
(b) a discharge nozzle for directing a stream of a pressurized gas/abrasive mixture from the container against a surface to abrade the surface;
(c) a gas delivery entry line for delivering a pressurized gas to the interior of the container through one of the conduits;
(d) an exit line communicating with the interior of the container and leading to the discharge nozzle;
(e) a pressure-actuated member that interrupts the flow of the gas/abrasive mixture from the container to the discharge nozzle, wherein when a pressurized gas is directed through the entry line into the inner conduit or intermediate passage, a pressure differential is created to draw the powdered abrasive material from the container out the exit line and to the nozzle.
Another aspect of this invention is a process for abrading a surface by delivering a stream of a mixture of a pressurized gas and a powdered abrasive material to the surface. The process comprises:
(A) connecting a source of pressurized gas to a hand-holdable apparatus that comprises
(a) a container-receiving member detachably attached to a container containing a powdered abrasive material;
(b) a discharge nozzle for directing the stream of the mixture of the gas/abrasive material against the surface;
(c) a first optionally flexible conduit having one end in fluid communication with the discharge nozzle and the other end in fluid communication with the attached container through the container-receiving member;
(d) a second optionally flexible conduit for connecting one end to an external gas source and the other end to the attachment portion for the abrasive material container;
(e) a manually-operated pinch valve for pinching either the first or second flexible conduit to regulate the flow of the mixture of the gas/abrasive material to the discharge nozzle; and
(f) a housing for parts (a)-(e),
(B) directing the discharge nozzle against a surface to be abraded, and
(C) actuating the pinch valve to allow a stream of pressurized gas/abrasive material to impinge upon the surface for a time sufficient to abrade the surface.
Another aspect of this invention is a process for abrading a surface by delivering a stream of a mixture of a pressurized gas and a powdered abrasive material. The process comprises
(A) connecting a source of pressurized gas to a hand-holdable apparatus that comprises
(a) an abrasive material pick-up assembly comprising (i) a container-receiving member for detachably receiving a container for the powdered abrasive material, (ii) two conduits, an inner conduit defined by a surrounding wall having a distal end away from the container-receiving member and proximal connected to the container-receiving member and an outer conduit defined by an outer wall, having analogous distal and proximal ends, wherein an intermediate passage is defined by the inner conduit wall and the outer-conduit wall, (iii) a container for holding the powdered abrasive material, the container having an open end and a closed end, which container is detachably connected to the container-receiving member through its open end and encloses the two conduits such that distal ends of the conduits are near the closed end of the container, (iv) a passageway through the wall of the inner conduit near its distal end, and (v) an optional passageway through the wall of the outer conduit near its distal end;
(b) a discharge nozzle for directing a stream of a pressurized gas/abrasive mixture from the container against a surface to abrade the surface;
(c) a pressurized gas delivery entry line for delivering a pressurized gas to the interior of the container through one of the conduits;
(d) an exit line communicating with the interior of the container and leading to the discharge nozzle;
(e) a pressure-actuated member that interrupts the flow of the gas/abrasive mixture from the container to the discharge nozzle, wherein when a pressurized gas is directed through the entry line into the inner conduit or intermediate passage, a pressure differential is created to force the powdered abrasive material from the container out the exit line and to the nozzle.
(B) directing a stream of gas/abrasive material from the discharge nozzle against a surface to be abraded, and
(C) allowing the pressurized gas to flow into the container to force the pressurized gas/abrasive material to impinge upon the surface for a time sufficient to abrade the surface.